M H Lehmann1, H Yang. 1. Department of Internal Medicine, Division of Cardiology, University of Michigan and Veterans Administration Medical Center, Ann Arbor, Michigan, USA.
Abstract
BACKGROUND: Previous characterizations of sex differences in ST-T waveform voltages have largely focused on amplitudes at selected time points during repolarization, subject to potential distortions from variations in heart rate (HR) or reliance on a JT-normalized time scale. METHODS AND RESULTS: Using digitized 12-lead ECGs from 553 normal adults (426 males) with HRs confined to 60+/-1, 70+/-1, or 80+/-1 bpm, we derived X, Y, and Z lead voltages and then generated, for each HR category by sex, summary (population mean) resultant spatial vector amplitudes (ST-T(XYZ)) and instantaneous slopes (dV/dt(XYZ)) at successive 4-ms intervals following the J point. Within each HR category, there was an early intersex divergence of ST-T(XYZ) trajectories (95% CIs nonoverlapping), with men exhibiting 2- to 3-fold greater dV/dt(XYZ) values during the ST segment and achieving greater maximum T(XYZ) and dV/dt(XYZ) values than women; descending T(XYZ) limbs were relatively more concordant between sexes but still steeper in men. The early sex differences in repolarization dynamics persisted in multiple regression analyses that took into account age and a morphometric index of left ventricular mass. In men, absolute values of extrema of T(XYZ) and dV/dt(XYZ) varied inversely with HR. CONCLUSIONS: At physiological resting HRs, the spatial ST-T vector voltage time trajectory is steeper in men than in women, beginning virtually from the J point. In addition to its mechanistic implications, the demonstration of marked sensitivity of ST-T(XYZ) and especially dV/dt(XYZ) to sex raises the possibility that these time-based, ECG-derived parameters might be informative in pathophysiological studies of ventricular repolarization.
BACKGROUND: Previous characterizations of sex differences in ST-T waveform voltages have largely focused on amplitudes at selected time points during repolarization, subject to potential distortions from variations in heart rate (HR) or reliance on a JT-normalized time scale. METHODS AND RESULTS: Using digitized 12-lead ECGs from 553 normal adults (426 males) with HRs confined to 60+/-1, 70+/-1, or 80+/-1 bpm, we derived X, Y, and Z lead voltages and then generated, for each HR category by sex, summary (population mean) resultant spatial vector amplitudes (ST-T(XYZ)) and instantaneous slopes (dV/dt(XYZ)) at successive 4-ms intervals following the J point. Within each HR category, there was an early intersex divergence of ST-T(XYZ) trajectories (95% CIs nonoverlapping), with men exhibiting 2- to 3-fold greater dV/dt(XYZ) values during the ST segment and achieving greater maximum T(XYZ) and dV/dt(XYZ) values than women; descending T(XYZ) limbs were relatively more concordant between sexes but still steeper in men. The early sex differences in repolarization dynamics persisted in multiple regression analyses that took into account age and a morphometric index of left ventricular mass. In men, absolute values of extrema of T(XYZ) and dV/dt(XYZ) varied inversely with HR. CONCLUSIONS: At physiological resting HRs, the spatial ST-T vector voltage time trajectory is steeper in men than in women, beginning virtually from the J point. In addition to its mechanistic implications, the demonstration of marked sensitivity of ST-T(XYZ) and especially dV/dt(XYZ) to sex raises the possibility that these time-based, ECG-derived parameters might be informative in pathophysiological studies of ventricular repolarization.
Authors: Najah Abi-Gerges; Ben G Small; Chris L Lawrence; Tim G Hammond; Jean-Pierre Valentin; Chris E Pollard Journal: Br J Pharmacol Date: 2004-07-20 Impact factor: 8.739
Authors: Vikram K Reddy; Susan M Gapstur; Ronald Prineas; Laura A Colangelo; Pamela Ouyang; Alan H Kadish Journal: Ann Noninvasive Electrocardiol Date: 2008-10 Impact factor: 1.468